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TUE POPULAR SCIENCE MONTELY.— SUPPLEMENT. 



of the region over which their action is felt in one 

 way or another, it can scarcely be doubted that 

 the earth's Vulcanian energies are at present 

 more actively at work throughout that region than 

 in any other. There is nothing so remarkable, 

 one may even say so stupendous, in the history 

 of subterranean disturbance as the alternation of 

 mighty earth-throes, by which, at one time, the 

 whole of the Chilian Andes seem disturbed, and 

 anon the whole of the Peruvian Andes. In Chili 

 scarcely a year ever passes without earthquakes, 

 and the same may be said of Peru ; but, so far 

 as great earthquakes are concerned, the activity 

 of the Peruvian region seems to synchronize with 

 the comparative quiescence of the Chilian region, 

 and vice versa. Thus, in 1797, the terrible earth- 

 quake occurred known as the earthquake of 

 Riobamba, which affected the entire Peruvian 

 earthquake region. Thirty years later a series 

 of tremendous throes shook the whole of Chili, 

 permanently elevating the whole line of coast to 

 the height of several feet. During the last ten 

 years the Peruvian region has in turn been dis- 

 turbed by great earthquakes. It should be added 

 that between Chili and Peru there is a region 

 about 500 miles in length in which scarcely any 

 volcanic action has been observed. And, singu- 

 larly enough, "this very portion of the Andes, to 

 which one would imagine that the Peruvians and 

 Chilians would fly as to a region of safety, is the 

 part most thinly inhabited — insomuch that, as 

 Von Buch observes, it is in some places entirely 

 deserted." 



One can readily understand that this enor- 

 mous double region of earthquakes, whose oscil- 

 lations on either side of the central region of 

 comparative rest may be compared to the sway- 

 ing of a mighty seesaw on either side of its 

 point of support, should be capable of giving 

 birth to throes propelling sea-waves across the 

 Pacific Ocean. The throe actually experienced 

 at any given place is relatively but an insignifi- 

 cant phenomenon ; it is the disturbance of the 

 entire region over which the throe is felt which 

 must be considered in attempting to estimate the 

 energy of the disturbing cause. The region 

 shaken by the earthquake of 1868, for instance, 

 was equal to at least a fourth of Europe, 

 and probably to fully one-half. From Quito 

 southward as far as Iquique — or along a full 

 third part of the length of the South American 

 Andes — the shock produced destructive effects. 

 It was also distinctly felt far to the north of 

 Quito, far to the south of Iquique, and inland to 

 enormous distances. The disturbing force which 



thus shook 1,000,000 square miles of the earth's 

 surface must have been one of almost inconceiv- 

 able energy. If directed entirely to the upheaval 

 of a land-region no larger than England, those 

 forces would have sufficed to have destroyed ut- 

 terly every city, town, and village, within such a 

 region ; if directed entirely to the upheaval of an 

 oceanic region, they would have been capable of 

 raising a wave which would have been felt on ev- 

 ery shore-line of the whole earth. Divided even 

 between the ocean on the one side and a land-re- 

 gion larger than Russia in Europe on the other, 

 those Vulcanian forces shook the whole of the 

 land-region, and sent athwart the largest of our 

 earth's oceans a wave which ran in upon shores 

 10,000 miles from the centre of disturbance with 

 a crest thirty feet high. Forces such as these 

 may fairly be regarded as cosmical ; they show 

 unmistakably that the earth has by no means set- 

 tled down into that condition of repose in which 

 some geologists still believe. We may ask with 

 the late Sir Charles Lyell whether, after contem- 

 plating the tremendous energy thus displayed by 

 the earth, any geologist will continue to assert 

 that the changes of relative level of land and sea, 

 so common in former ages of the world, have 

 now ceased ? and agree with him that if, in the 

 face of such evidence, a geologist persists in 

 maintaining this favorite dogma, it would be vain 

 to hope, by accumulating proofs of similar con- 

 vulsions during a series of ages, to shake the 

 tenacity of his conviction — 



" Si fractuB illabatur orbis, 

 Impavidum ferient ruins." 



But there is one aspect iu which such mighty 

 sea-waves as in 1868, and again last May, have 

 swept over the surface of our terrestrial oceans, 

 remains yet to be considered. 



The oceans and continents of our earth must 

 be clearly discernible from her nearer neighbors 

 among the planets — from Venus and Mercury on 

 the inner side of her path around the sun, and 

 from Mars (though under less favorable condi- 

 tions) from the outer side. When we consider, 

 indeed, that the lands and seas of Mars can be 

 clearly discerned with telescopic aid from our 

 earth at a distance of 40,000,000 miles, we per- 

 ceive that our earth, seen from Venus at little 

 more than half this distance, must present a very 

 interesting appearance. Enlarged, owing to great- 

 er proximity, nearly fourfold, having a diameter 

 nearly twice as great as that of Mars, so that at 

 the same distance her disk would seem more than 

 three times as large, more brightly illuminated 

 by the sun in the proportion of about five to tw 



